“Bite-Size Bits of Local, National, and Global History”
“Bite-Size Bits of Local, National, and Global History”
Mackinaw City in Emmet County, Michigan — The American Midwest (Great Lakes)

Crossing the Straits

An engineer up to the task

Crossing the Straits Marker image. Click for full size.
Photographed By Mike Wintermantel, July 2, 2022
1. Crossing the Straits Marker
Inscription.  The Mackinac Bridge A Long-Term Success
More than 60 years old, the Mackinac Bridge is still the longest suspension bridge in the western hemisphere. The world's longest, the Akashi-Kaikyo Bridge in Japan, was only built in 1998 after the Japanese engineers visited the Mackinac Bridge and conferred with the "Mack's" engineers and maintenance workers.

Handling the wind
The Mackinac Bridge across the Straits of Mackinac was under discussion for decades before it moved from a dream to a plan. Many factors deterred progress, not the least being the daunting weather. A bridge would have to withstand the "savage winds" and "pile-driving ice."
Dr. David B. Steinman was the engineer chosen to design the perfect bridge, a bridge in harmony with nature, a bridge solid enough to divert driving ice yet lacy enough to shrug off the winds.
The best way to deal with high winds was to offer no resistance. Steinman designed an openwork system for the bridge superstructure. The trusses under the roadbed are open, half of the roadbed surface is open, and the railings are low and open. The wind flows through the Bridge
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like water through a sieve. In Steinman's day the highest recorded wind across the Straits had been 78 mph. His design, stable up to winds of 632 mph, was further stabilized to the point that today engineers report the bridge can withstand winds of 1,000 mph, far out-pacing the Golden Gate's meager 40 mph design specs.
The wind speed record in the Straits today is 121 mph.

Handling the Ice
The grinding ice would eat away the piles supporting it. "Ice floes could produce pressures of up to 23,000 pounds per lineal foot of pier width-10 tons of pressure per foot!" The piers were designed as telescoping tubes, each higher was narrower. The piers are massive just below the water line but narrow considerably at the surface where they have contact with the ice. These narrow piers take less pounding and are designed to handle five times the expected ice pressure. To combat the corrosive power of the grinding ice the piers are wrapped in armor plate steel from a height exposed at low water to the height at high water-a range of many feet.

Dr. David B. Steinman
Who would build the needed bridge?

In 1940, when building a bridge got serious, several bridge engineers expressed an interest. One was L.S. Moiseiff, the consulting engineer in the 1937 Golden Gate Bridge and the designer of the 1938 Tacoma Narrows Bridge. Having dealt with
Crossing the Straits Marker image. Click for full size.
Photographed By Mike Wintermantel, July 2, 2022
2. Crossing the Straits Marker
these two bridges, similar to the bridge needed in the Straits of Mackinac, he was a logical choice for design engineer.
Because of the slow recovery from the Great Depression followed by WWII nothing was done until the 1950s, giving the Tacoma Narrows Bridge time to twist apart in a spectacular collapse and thus eliminate Moiseiff from consideration.
Dr. David Steinman actively pursued the job and was chosen as the engineer. He had build notable bridges on five continents and received many civil engineering awards including awards for beauty. Design inspiration came from his childhood living under the Brooklyn Bridge. He stressed that the Mackinac Bridge needed to be beautiful as well as safe and functional.

Bridge color
Steinman disliked the typical black and grey paint used for bridges. He said he wanted "to get away from these sad, somber, cold colors an into something warm and bright to harmonize with and be a part of the landscape."
The green and ivory colors resulted from a magazine advertisement featuring the bridge, crafted before the official colors were decided.
Bridge decision makers liked the magazine rendering and used these colors. (No, the colors were not chosen to support Michigan State!)
Erected by McGulpin Point Discovery Trail.
Topics. This historical marker is listed in these
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topic lists: Bridges & ViaductsWaterways & Vessels. A significant historical year for this entry is 1998.
Location. 45° 47.225′ N, 84° 46.368′ W. Marker is in Mackinaw City, Michigan, in Emmet County. Located on the grounds of the McGulpin Point Lighthouse. Touch for map. Marker is at or near this postal address: 500 Headlands Road, Mackinaw City MI 49701, United States of America. Touch for directions.
Other nearby markers. At least 8 other markers are within walking distance of this marker. Chi-Sin Trail (here, next to this marker); Keeper 1879-1906 (a few steps from this marker); Cedarville (a few steps from this marker); Carl D. Bradley (a few steps from this marker); Eber Ward (a few steps from this marker); James W. Bennett (a few steps from this marker); Minneapolis (a few steps from this marker); William H. Barnum (within shouting distance of this marker). Touch for a list and map of all markers in Mackinaw City.
Credits. This page was last revised on July 5, 2022. It was originally submitted on July 5, 2022, by Mike Wintermantel of Pittsburgh, Pennsylvania. This page has been viewed 131 times since then and 30 times this year. Photos:   1, 2. submitted on July 5, 2022, by Mike Wintermantel of Pittsburgh, Pennsylvania.

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Apr. 24, 2024